Process for preparing

ABSTRACT

The invention is directed to a process for preparing a bis(hydroxymethyl)perylenetetracarboximide compound by reacting perylene-3,4,9,10-tetracarboximide with formaldehyde. The bis(hydroxymethyl)perylenetetracarboximide can be isolated or further reacted in a one pot synthesis to yield a compound of the formula                    
     wherein X 1  and X 2  are organic radicals.

SUMMARY

The invention relates to a process for preparing bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide wherein perylene-3,4,9,10-tetracarboximide is reacted with formaldehyde to yield the title compound, which is isolated or further reacted to form perylene derivatives which are useful as colorants for pigmenting high molecular weight organic materials.

BACKGROUND

Compounds from the class of the perylenetetracarboximides, or peryleneimides for short, have long been known in the art and are produced on an industrial scale. The compounds are recognized as being valuable colorants for high molecular weight organic materials.

U.S. Pat. No. 4,762,569 discloses N-substituted derivatives of perylene which are useful as dispersing agents for various pigments in non-aqueous media. The derivatives are prepared by reacting an amine, such as dimethylaminopropylamine, methylaminopropylaniine and the like, with tetracarboxylic acid dianhydnde of per-substituted condensed benzene ring of perylene. JO 1217056 discloses N-substituted derivatives of a perylene which are useful as dispersing agents for diketopyrrolopyrrole pigments in inks and paints obtained by a dispersion method. Perylene, for example, is reacted with dimethylbenzoguanamine, followed by reaction with tetrachlorophthalimide.

The present invention relates to a process for preparing a variety of N-substituted derivatives of perylene pigments wherein the N-substituted are linked to the perylene moiety by —CH₂— or —O—CH₂— linkages. The inventive process involves reacting perylene-3,4,9,10-tetracarboximide with formaldehyde to yield a bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide intermediate and further reacting the intermediate, with or without isolation, with a second reactant which reacts with the hydroxymethyl groups. The products of the reaction are useful as colorants for a variety of organic materials of high molecular weight. The bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide intermediate is useful as a colorant and as a synthon for the preparation of a variety of perylene derivatives and as a stabilizer for polymers.

DETAILED DESCRIPTION

The process according to the invention relates to a process of preparing a perylene derivative of the formula (I)

wherein X₁ and X₂, each independently of the other, are organic radicals, D is chlorine or bromine, and n is an integer from 0 to 4; which perylene derivative contains from 0 to 6 moles of —SO₃M per mole of the perylene derivative, wherein M is hydrogen or a metal or ammonium cation, which process comprises reacting perylene-3,4,9,10-tetracarboximide of the formula

in a first step with formaldehyde to yield a sulfonated or non-sulfonated form of bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide of the formula

which intermediate reacts in a second step with a precursor of the organic radicals, X₁ and X₂, to yield the sulfonated or non-sulfonated form of the perylene derivative of formula (I). In general, the second reactant reacts with the bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide by a substitution reaction or by forming an —O— linkage.

The first step is preferably carried out by adding the perylene-3,4,9,10-tetracarboximide to a solution of paraformaldehyde in oleum (fuming sulfuric acid), concentrated sulfuric acid or polyphosphoric acid. The perylene-3,4,9,10-tetracarboximides of the above formula are known in the art and are commercially available.

When the reaction is carried out in concentrated sulfuric acid, some sulfonation occurs depending on the reaction temperature: the higher the temperature, the higher the degree of sulfonation. Reaction products containing very low to no sulfonation can be obtained under controlled conditions. The degree of sulfonation may be deliberately increased by using oleum, and the degree of sulfonation can be varied by using different reaction temperatures. Sulfur-free compounds can be easily prepared by employing polyphospheric acid as the reaction medium.

In general, a stoichiometic amount of formaldehyde is used in the first step. It is convenient to use paraformaldehyde although anhydrous formaldehyde also serves the purpose. Thus, the molar ratio of the perylene-3,4,9,10-tetracarboximide to the formaldehyde during the first step is preferably 1:2.

After the first step is complete, the resulting bis(hydroxymethyl) intermediate is reacted with the precursor or a different substrate to yield the perylene derivative of formula (I).

Preferably, both steps are carried out at a temperature of from 20 to 100° C. If a high degree of sulfonation is desired, the process is carried out at high temperatures, for example above 40° C., preferably using fuming sulfuric acid. If it is desirable to have a low degree of sulfonation, the reaction is maintained at a lower temperature, preferably 40° C. or below, preferably using concentrated sulfuric acid.

When using polyphosphoric acid as the reaction medium, it is advantageous to run the reaction at a temperature of between about 50 and 180° C., preferably between about 60 and 150° C., and most preferably between about 80 and 130° C. It is advantageous to employ a ratio of 1:4 of perylene diimide to polyphosphoric acid on a weight basis, with higher ratios, i.e., 1:20 or 1:10, also being possible if necessary.

After the reaction is complete, the perylene derivative is isolated by procedures conventionally used in the art for isolating perylenes, in particular by pouring the acid solution onto ice water while maintaining the temperature below 10° C., stirring the resulting aqueous slurry, followed by filtration, washing with water and drying to yield the perylene derivative in solid form.

Since it is not necessary to isolate the intermediate, the process according to the invention is preferably a one pot process. However, it is possible to isolate the intermediate prior to carrying out the second step, especially, for example, in those instances where it is desirable to carry out the second step in a solvent other than the solvent used in the first step.

Suitable solvents for the second step include concentrated sulfuric acid, fuming sulfuric acid, polyphosphoric acid and organic solvents which do not react with the bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide intermediate, especially polar organic solvents such as acetonitrile, benzonitrile, dimethylformide, dimethylsulfoxide, tetramethylenesulfone and the like.

It is also possible to carry out the second step in a solvent which reacts with the bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide intermediate to yield the desired product. For example, C₁-C₁₀alcohols are suitable solvents if the compound of formula (I) is the ether obtainable by reacting the bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide intermediate with the alcohol.

Preferably, the perylene derivatives of formula (I) contain from 0 to 4 moles of —SO₃M per mole of the perylene derivative; most preferably from 0 to 2 moles per mole of perylene derivative. In general, if the reaction is carried out at about 40-50° C. in concentrated sulfuric acid, the product contains about 0 to 1.5 moles of —SO₃M per mole of the perylene derivative. If the reaction is carried out at about 40-60° C. in fuming sulfuric acid, the product contains about 1 to 6 moles of —SO₃M per mole of the perylene derivative, depending on the structural features of the second reactant.

M is preferably hydrogen, or an alkali metal, such as sodium or potassium, an alkaline earth metal, such as magnesium, an aluminum, a zinc or an ammonium cation. Examples of suitable ammonium cations include quaternary ammonium cations, such as trimethylcetylammonium or tributylbenzylammonium.

The organic radicals X₁ and X₂ are derivable from a precursor which reacts with the hydroxy groups of the bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide either by a substitution reaction or to form an —O— linkage.

Precursors which react with a hydroxyl group by a substitution reaction are generally compounds which comprise an aromatic radical, a heteroaromatic radical, or radicals of the formulae Q—C(═O)—Y—, —Y—C(═O)—O—Q, Q—C(═S)—Y—, —Y—C(═S)—O—Q, —Y—C(═S)—S—Q, Q—C(═N)—Y—, QZN—, Q—SO₂—NR₁,

N(R₁)—C(═O)—O—Q; wherein Q and Z are each hydrogen or an aliphatic, alicyclic, araliphatic, aromatic or heterocyclic radical, or Q and Z together form a 3 to 8 membered ring; Y is the residue of an active methylene containing moiety; and R₁ is hydrogen, an aliphatic radical, an alicyclic radical, an araliphatic radical, an aromatic radical or a heterocyclic radical; or R₁ and Q together form a 3 to 8 membered ring.

Examples of X₁ and X₂ radicals derivable from a precursor which reacts with a hydroxyl group to form an —O— linkage include an alkyl halide and radicals of the formulae Q—C(═O)O—, Q—C(═S)O—, Q—SO₂—O—, QO—; wherein Q has the meaning given above.

As aromatic radicals, X₁ and X₂ especially include radicals containing 1, 2, 3, 4 or more phenyl rings which are bonded directly to each other, bonded to each other through a lining group, fused or any combination thereof The biphenyl radical is an example of two phenyl rings directly bonded to each other. Radicals of the formulae

wherein G₁ is a linking group, are examples of phenyl rings bonded through each other through a linking group. Examples of aromatic radicals containing fused phenyl rings include naphthyl, anthryl and phenanthryl.

The liking group G₁ is especially —O—, NR₂—, N═N or —SO₂—.

As heteroaromatic radicals, X₁ and X₂ especially include radicals containing one or more 5, 6 or 7 membered aromatic rings containing from 1 to 4 heteroatoms. In general, the heteroatom(s) are nitrogen, oxygen, sulfur or any combination thereof Suitable heteroaromatic radicals include the pyrrolopyrroles, especially the 1,4-diketo-3,6-diarylpyrrolo[3,4-c]pyrroles and quinacridones.

Y is the residue of an active methylene containing moiety. Active methylene moieties are generally those methylene groups which are linked to an electron withdrawing substituent, such as a carbonyl or nitrile substituent. In general, active methylene moieties participate in a Mannich type or similar reaction. In general, Y is —CHQ, —CH₂—Q or —(CH═CH)n—CH₂—Q, wherein n is 1, 2 or 3. When Y is the —CHQ— radical, the —CHQ— radical is part of a ring, for example, when X₁ or X₂ is the Q—C(═O)—Y—radical, Q and Y can form part of, for example, a cyclohexanone ring.

Q and Z are aliphatic, alicyclic, araliphatic, aromatic or heterocyclic radicals.

In general, aliphatic radicals include C₁-C₁₀alkyl, C₁-C₁₀alkenyl, and C₁-C₁₀alkynyl radicals, including straight and branched chains.

Alicyclic radicals include those moieties containing only one or more nonaromatic hydrocarbon rings. Important alicyclic radicals derived from C₃-C₈cycloalkanes and C₃-C₈cycloalkenes. Examples of important alicyclic radicals include cyclopentyl, cyclohexyl and cycloheptyl. Alicyclic radicals also include those moieties wherein there is, for example, a —C(═O)— on the ring, such as cyclohexanone.

Araliphatic radicals are those moieties which contain an aliphatic portion and an aromatic portion, for example a phenyl or heteroaromatic portion. Examples of araliphatic radicals include radicals derived from the phenylalkanoic acids, the naphthylalkanoic acids, the pyridine alkanoic acids, the quinoline alkanoic acids, the indole alkanoic acids, such as those derived from phenyl acetic acid, phenyl propionic acid or indole acetic acid.

Aromatic radicals suitable as Q and Z include those described above as being useful as X₁ and X₂. The term “aromatic” radical, in this instance, does not include heteroaromatic radicals.

Heterocyclic radicals contain one or more nonaromatic and/or aromatic rings which contain one or more heteroatoms; especially 3 to 8 membered rings which contain 1 to 3 heteroatoms, which heteroatoms are especially nitrogen, sulfur and oxygen. The term heterocyclic radical includes fused ring systems wherein one or more rings contain one or more heteroatoms. Important heterocyclic radicals include pyridinyl, pyranyl, tetrahydrofuranyl, morpholino, pyrimidyl, pyrone, oxazine, azepinyl, triazinyl, oxathiazinyl, pyrrolyl, benzofuranyl, piperazinyl, oxathiazolyl, oxadiazolyl, quinolinyl, indolyl, carbazolyl, xanthenyl, acridinyl, coumarinyl, benzoxazolyl, benzopyrone, quinazolinyl. Heterocyclic radicals include those wherein the ring is a lactone or a lactam.

The description of radicals above also defines aliphatic, alicyclic, araliphatic, aromatic and heterocyclic radicals suitable as R₁. When R₁ combines with Q to form a ring, the ring is preferably a five or six membered ring.

The aromatic, heterocyclic, aliphatic, alicyclic and araliphatic radicals are unsubstituted (by any group other than hydrogen) or substituted by one or more, preferably 0 to 4, customary substituted.

Customary substituted include hydroxyl, carbonyl, halogen, C₁-C₁₈alkyl, C₁-C₁₈alkoxy, C₁-C₁₈alkylmercapto, C₁-C₁₈alkylamino, di(C₁-C₁₈alkyl)amino, C₁-C₁₈alkoxycarbonyl, C₁-C₁₈alkylaminocarbonyl, —CN, —NO₂, trifluoromethyl, C₅-C₆cycloalkyl, —C═N—C₁-C₁₈alkyl) and phenyl, wherein the alkyl groups can be further substituted by hydroxyl, halogen, nitro, C₁-C₆alkoxy, carbonyl, —CN.

Substitutents defined as halogen are typically iodo, fluoro, bromo and, preferably, chloro.

C₁-C₆Alkyl is typically methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-amyl, tert-amyl, hexyl, and C₁-C₁₀alkyl. C₁-C₁₈Allkyl are in addition typically heptyl, octyl, 2-ethylhexyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl or octadecyl.

C₁-C₁₈Alkoxy, also in C₁-C₁₈alkoxycarbonyl, is typically methoxy, ethoxy, n-propoxy, isopropoxy, butoxy, hexyloxy, decyloxy, dodecyloxy, hexadecyloxy or octadecyloxy.

C₁-C₁₈Alkylamino is, also in C₁-C₁₈alkylaminocarbonyl, typically methylamino, ethylamino, propylamino, hexylamino, decylamino, hexadecylamino or octadecylanino.

C₅-C₆Cycloalkyl is typically cyclopentyl and cyclohexyl.

Important radicals containing the residue of an active methylene, Y, include radicals derivable from various acetoacetanilides, cyanoacetanilides and benzoylacetanilides, such as ethylacetoacetate, ethyl malonate, ethyl cyanoacetate, ethyl benzoyl acetate and malononitrile.

Important radicals of the formula Q—C(═O)—O— include esters derivable from C₁-C₂₄aliphatic acids, such as acetic acid, stearic acid, oleic acid, linoleic acid, acrylic acid, methacrylic acid or trifluoroacetic acid, a C₆-C₂₄araliphatic acid, such as benzoic acid, phenyl acetic acid, phenyl propionic acid or indole acetic acid, a resin acid, such as abeitic acid, behemic acid, a naphthenic acid, a dimeric acid, wherein the aliphatic acids and araliphatic acids are unsubstituted or substituted by one or more customary substituents.

Important radicals of the formulae Q—C(═O)—NR₁— and Q—SO₂—NR₁— include those derivable from amides and sulfonamides prepared from an aliphatic amine and an aliphatic carboxylic or sulfonic acid, an aromatic amine and an aliphatic carboxylic or sulfonic acid, or an aromatic amine and an aromatic or araliphatic carboxylic or sulfonic acid. Suitable radicals of the formulae Q—C(═O)NR₁ and Q—SO₂—NR₁ especially include those wherein Q is C₁-C₂₄alkyl, phenyl, benzyl, tolyl, naphthyl and R₁ is hydrogen, methyl, ethyl, n-propyl, isopropyl, phenyl, benzyl.

Important radicals of the formulae Q—SO₂—, Q—SO₂O— and Q—C(═S)—O— include those wherein Q is a C₁-C₂₄aliphatic radical, a C₆-C₁₈aromatic radical, a C₁-C₂₄araliphatic radical, a 5, 6 or 7 membered heterocyclic ring, or a fused ring system containing a 5, 6 or 7 membered heterocyclic ring, such as pentyl hexyl, phenyl, benzyl, tolyl, naphthyl, pyridinyl or indolyl. Important radicals of the formula Q—SO₂—O— include those derivable from p-toluene sulfonic acid, naphthalene sulfonic acid, pentane sulfonic acid or a water-soluble dye which contains an —SO₃H water-solubilizing group.

Important radicals of the formula QZN— include those derivable from N,N-diC₁-C₂₄alylamines, such as diethylamine, diethylamine, dipropylamine and dibutylamine, arylamines, such as N,N-diphenylamine, aralkylamines, such as N,N-dibenzylamine or ethylphenylamine, or heteroaryl amines, such as aminopyridine. The formula QZN— also includes those radicals wherein Q and Z, together, along with the nitrogen atom to which they are bonded, from a 3 to 8 membered ring, especially a 5 or 6 membered ring, such as piperazine, morpholine, thiomorpholine, pyrrolidone or piperidine.

Important radicals of the formula QO— include those wherein Q is a C₁-C₂₄aliphatic radical, a C₅-C₁₀alicyclic radical, phenyl, benzyl, naphthyl or a radical H—(CH₂CHR₃O)_(m)—CH₂CHR₃—, wherein R₃ is hydrogen or methyl, especially hydrogen, and m is a number from 1 to 20.

Important radicals of the formula QS— include those wherein Q is a C₁-C₂₄ aliphatic radical, a C₅-C₁₀alicyclic radical, phenyl, benzyl and naphthyl.

Important radicals of the formulae

include radicals derivable form succinimide, glutarimide, phthalide, naphthalimide and isoquinoline-1,3-dione.

Important radicals of the formula —N(R₁)—C(═O)—O—X include those wherein R₁ is hydrogen, C₁-C₆alkyl, phenyl or benzyl, especially hydrogen and C₁-C₆alkyl, and Q is C₁-C₆alkyl, for example, urethane.

Aromatic and heteroaromatic radicals derivable from known dyes, such as azo, azomethine, or fiber-reactive dyes, for example triazine dyes, or known organic pigments, such as diketopyrrolopyrrole, quinacridone, phthalocyanine, indanthrone, isoindoline, isoindolone, flavanthrone, pyranthrone, anthraquinone, thioindigo, perylene and dioxazine pigments are suitable radicals for X₁ and X₂. Quinacridyl (derived from a quinacridone) and 1,4-diketo-3,6-diarylpyrrolo[3,4-c]pyrrolyl (derived from a 1,4-diketo-3,6-diarylpyrrolo[3,4-c]pyrrole) radicals are especially suitable radicals for X₁ and X₂.

Thus, an aspect of the present invention relates to a process of preparing perylene derivatives of the formula (I) wherein X₁ and X₂ are each a pigment moiety, in particular, a diketopyrrolopyrrole, quinacridone, phthalocyanine, indanthrone, isoindoline, isoindolone, flavanthrone, pyranthrone, anthraquinone, thioindigo, perylene or dioxazine pigment moiety.

1,4-diketo-3,6-diarylpyrrolo[3,4-c]pyrrolyl radicals are especially suitable radicals for X₁ and X₂. Such radicals are derivable from compounds of formula

which are well known pigments.

When X₁ and X₂ are 1,4-diketo-3,6-diarylpyrrolo[3,4-c]pyrrolyl radicals, the preferences described above for A₁ and A₂ apply.

Another aspect of the invention relates to a process for preparing perylene derivatives of formula (I) wherein X₁ and X₂ are quinacridinyl radicals. Such radicals are derivable from the compounds of the formula

wherein each R₄ is independently hydrogen, halogen, caiboxyl, unsubstituted C₁-C₆alkyl, C₁-C₆alkoxy which is substituted by halogen.

X₁ and X₂ are especially radicals derivable from quinacridone, 2,9-dichloroquinacridone, 4,11-dichloroquinacridone, 2,9-dimethylquinacridone, 4,11-dimethylquinacridone or 2,9-difluoroquinacridone.

The present invention also relates to the intermediate compound bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide which contains from 0 to 6 moles of —SO₃M per mole of said compound, wherein M is hydrogen or a metal or ammonium cation.

Preferably, the intermediate compound has from 0 to 4 moles of —SO₃M, most preferably from 0 to 2 moles of —SO₃M.

The present invention further relates to a process for preparing the intermediate compound bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide which contains from 0 to 6 moles of —SO₃M per mole of said compound, wherein M is hydrogen or a metal or ammonium cation, which process comprises reacting a perylene of the formula

wherein D is chlorine or bromine and n is an integer from 0 to 4, with formaldehyde or paraformaldehyde.

The preferences discussed above relating to the first step of the process for preparing the intermediate compound are applicable to this aspect of the invention.

In particular, the present invention relates to the process wherein the perylene compound is combined with paraformaldehyde in concentrated sulfuric acid, oleum (fuming sulfuric acid) or polyphosphoric acid; especially wherein the perylene compound and formaldehyde are present in a molar ratio of about 0.75:2 to 1.25:2, most preferably of about 1:2.

If less sulfonation is desired, the reaction is carried out at a temperature of 40° C. or below using concentrated sulfuric acid. The reaction generally proceeds at higher temperatures, for example, in the range from about 20 to about 120° C., but higher temperatures generally lead to a higher degree of sulfonation. The use of oleum further contributes to a higher degree of sulfonation, whereas the use of concentrated sulfuric acid has been observed to result in a lower degree of sulfonation. A higher degree of sulfonation may be desirable depending on the intended use of the final product.

It is also possible to employ polyphosphoric acid in the reaction, which of coarse results in no sulfonation. It is desirable to use a sufficient amount of polyphosphoric acid such that the reactants are readily stirrable at the reaction temperature. Such amount is typically about a 1:4 weight ratio of polyphosphoric acid to reactants. It is convenient to carry out the reaction using higher amounts of polyphosphoric acid up to 10 to 20 times the weight of the reactants. It is important to maintain a reaction temperature sufficient to render the reactants readily stirrable as well as ensuring an effective condensation reaction. An effective temperature is typically on the order of from about 50 to 180° C., preferably from 60 to 150° C. and more preferably from 80 to 130° C.

The intermediate hydroxymethyl compound is generally isolated by precipitation and filtration, for example by drowning in an organic solvent or water followed by filtration.

In addition to being useful as an intermediate to prepare the perylene compounds of formula (I), the bis(hydroxymethyl) perylene-3,4,9,10-tetracarboximide is useful as a colorant and stabilizer for polymers.

The perylene derivatives of formula (I) are useful as colorants, such as pigments and dyes, for a variety of materials, in particular paints, plastics, fibers and inks, and as property enhancing agents in pigment compositions, for example as rheology improvers in paints and heat stabilizers in engineering polymers.

In general, the perylene derivatives of formula (I) with a lower degree of sulfonation are most suitable as pigments, while those with a higher degree of sulfonation are useful as dyes and additives.

The following examples are for purposes of illustration, and are not intended to limit the scope of the present invention in any manner whatsoever. Parts and percentages are by weight unless otherwise noted.

EXAMPLE 1 Bis(hydroxymethyl)perylene-3,4,9,10-tetracarboximide

Concentrated sulfuric acid (96%, 250 grams) are added to a one-liter four-necked round-bottomed flask equipped with a stirrer, thermometer and reflux condenser with a drying tube. Paraformaldehyde (1.6 grams, 0.052 mole) is then introduced into the sulfuric acid followed by the addition of small portions of perylene-3,4,9,10-tetracarboximide (9.8 grams, 0.0251 mole), maintaining the pot temperature between 40 and 45° C. The reaction mixture is stirred at 45±3° C. for 4.0 hours and then poured into ice water, filtered, washed with water until the filtrate is acid free, dried and pulverized, affording 11.1 grams (98.2% of theory) of a violet colored solid.

The isolated product analyzes as C₂₆H₁₄N₂O₆ corresponding to bis(hydroxymethyl)perylene-3,4,9,10-tetracarboximide.

EXAMPLE 2

Concentrated sulfuric acid (96%, 250 grams) are added to a one-liter four-necked round-bottomed flask equipped with a stirrer, thermometer and a reflux condenser with a drying tube. Paraformaldehyde (1.6 grams, 0.052 mole) is then introduced into the sulfuric acid followed by the addition of small portions of perylene-3,4,9,10-tetracarboximide (9.8 grams, 0.0251 mole), maintaining the pot temperature between 40 and 45° C. The reaction mixture is stirred at 45±3° C. for one hour to ensure complete solution. To this solution is added unsubstituted quinacridone (15.6 grams, 0.05 mole) in small portions maintaining the pot temperature below 40° C. The mixture is stirred at 45±3° C. for 3 hours, poured into ice water, filtered, washed with water until the filtrate is acid fee, dried and pulverized to yield 26.0 grams (99.7% of theory) a small particle sized maroon colored pigment.

The isolated product analyzes as C₆₆H₃₄N₆O₈ corresponding to the perylene diimide derivative of the formula

EXAMPLE 3

The same general procedure of Example 2 is followed, except using 4,11-dichloroquinacridone (19.05 grams, 0.05 mole) in place of the unsubstituted quinacridone. The product (27.0 grams, 97.1% of theory) is a small particle sized burnt orange colored pigment.

The product analyzes as C₆₆H₃₀Cl₄N₆O₈ corresponding to the perylene diimide derivative of the formula

EXAMPLE 4

The same general procedure of Example 2 is followed, except using perylene-3,4,9,10-tetracarboximide (19.5 grams, 0.05 mole) in place of the unsubstituted quinacridone. The product is a small particle sized violet colored pigment obtained in quantitative yield.

The product analyzes as C₇₄H₃₀N₆O₁₂ corresponding to the perylene diimide derivative of the formula

EXAMPLE 5

The same general procedure of Example 2 is followed, except using 3,6-di(4-chlorophenyl)-pyrrolo[3,4-c]pyrrol-1,4-dione (17.9 grams, 0.05 mole) in place of the unsubstituted quinacridone. The product is a small particle sized violet colored pigment obtained in quantitative yield.

The product analyzes as C₆₂H₃₀Cl₄N₆O₈ corresponding to the perylene diimide derivative of the formula

EXAMPLE 6

The same general procedure of Example 2 is followed, except using 3,6-di(4-methylphenyl)-pyrrolo[3,4-c]pyrrol-1,4-dione (15.8 grams, 0.05 mole) in place of the unsubstituted quinacridone. The product is a small particle sized reddish violet colored pigment obtained in quantitative yield.

The product analyzes as C₆₆H₄₂N₆O₈ corresponding to the perylene diimide derivative of the formula

EXAMPLE 7

The same general procedure of Example 2 is followed, except using 3,6-di(4-tert-butylphenyl)-pyrrolo[3,4-c]pyrrol-1,4-dione (20.0 grams, 0.05 mole) in place of the unsubstituted quinacridone. The product is a small particle sized reddish violet colored pigment obtained in quantitative yield.

The product analyzes as C₇₈H₆₆N₆O₈ corresponding to the perylene diimide derivative of the formula

EXAMPLE 8

Fuming concentrated sulfuric acid (15% oleum with a free —SO₃ content of 12.0-17.0%, 250 grams) are added to a one-liter four-necked round-bottomed flask equipped with a stirrer, thermometer and a reflux condenser with a drying tube. Paraformaldehyde (1.6 grams, 0.052 mole) is then introduced into the sulfuric acid followed by the addition of small portions of perylene-3,4,9,10-tetracarboximide (9.8 grams, 0.0251 mole), maintaining the pot temperature between 40 and 45° C. The reaction mixture is stirred at 45±3° C. for one hour to ensure complete solution. To this solution is added unsubstituted quinacridone (15.6 grams, 0.05 mole) in small portions maintaining the pot temperature below 40° C. The mixture is stirred at 45±3° C. for 3 hours, poured into ice water, filtered, washed with water until the filtrate is acid fee, dried and pulverized to yield a small particle sized dark brown colored pigment (89% of theory).

Sulfur analysis for the isolated product indicates four to five sulfonic acid groups attached to the perylene diimide derivative of the formula

EXAMPLE 9

Polyphosphoric acid (115% content of H₃PO₄ from Aldrich, 300 grams) are added to a one-liter four-necked round-bottomed flask equipped with a stirrer, thermometer and a reflux condenser with a drying tube. Paraformaldehyde (1.6 grams, 0.052 mole) is then introduced into the polyphosphoric acid followed by the addition of small portions of perylene-3,4,9,10-tetracarboximide (9.8 grams, 0.0251 mole), maintaining the pot temperature between 90 and 105° C. The reaction mixture is stirred at 105±3° C. for 1.5 hours to ensure complete reaction. To this reaction mixture is added unsubstituted quinacridone (15.6 grams, 0.05 mole) in small portions maintaining the pot temperature below 120° C. The mixture is stirred at 125±3° C. for 3 hours, poured into ice water, filtered, washed with water until the filtrate is acid fee, dried and pulverized to yield a small particle sized maroon colored pigment obtained in quantitative yield.

The isolated product analyzes as C₆₆H₃₄N₆O₈ corresponding to the perylene diimide derivative of the formula 

What is claimed is:
 1. A process for preparing a compound of the formula (II)

which contains from 0 to 6 moles of —SO₃M per mole of the compound, wherein D is chlorine or bromine and n is an integer from 0 to 4 and M is hydrogen or a metal or ammonium cation, which process comprises reacting perylene-3,4,9,10-tetracarboximide of the formula

with formaldehyde.
 2. The process of claim 1 wherein the perylene-3,4,9,10-tetracarboximide is combined with formaldehyde in concentrated sulfuric acid.
 3. The process of claim 2 wherein the process is carried out at a temperature of 40° C. or below.
 4. The process of claim 1 wherein the perylene-3,4,9,10-tetracarboximide is combined with formaldehyde in oleum.
 5. The process of claim 4 wherein the process is carried out at a temperature of 40° C. or above.
 6. The process of claim 1 wherein the perylene-3,4,9,10-tetracarboximide is combined with formaldehyde in polyphosphoric acid.
 7. The process of claim 6 wherein the process is carried out at a temperature of between 50 and 180° C. 